Robert Greiner

Prediction and calculation of the shear creep behaviour of amorphous polymers under progressing physical ageing

Abstract The shear creep behaviour of polystyrene PS N 7000 under the influence of physical ageing is thoroughly investigated. The theory of linear viscoelastic behaviour under the influence of ageing at constant temperature is briefly reviewed. Emphasis is given to the evaluation of the time-age shift function from creep experiments as well as to finding a suitable theoretical description of the time-age shift function and the creep behaviour. It has been shown that the multiparameter model based on free volume leads to an excellent description and prediction of the ageing behaviour in shear creep at constant temperature after various preconditioning times and at various ageing temperatures. Taking into account the history of the sample prior to the creep experiment, the creep behaviour under all given conditions is predicted from only one optional equilibrium creep curve.